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1976 90 hp mercury

merckurt

New member
"HI, I HAVE A 1979 6 CYL. 90 HP. OUTBOARD. POWER HEAD BAD.WOULD THE LOWER UNIT FIT A 1972 80 HP. 4 CYL. OR CAN I PUT THE TILT AND TRIM FROM 90 HP. ON THE 80 HP ? THANK'S KURT"
 
"They are inline motors,you sh

"They are inline motors,you should be able to switch power heads,but to be sure measure the bolt spacing."
 
"Oh you may need to change the

"Oh you may need to change the exhaust tube,two different part #'s,78184T is on the 90HP,38470 is the # for the 80HP."
 
"I think you will find that th

"I think you will find that the gear ratio's are different as well.

Not a big deal if they are but it would mean that your existing prop may not be viable.

I'm thinking the older 80 horse models ran 2.3:1 gears while the 90's ran 1.78:1.

If my memory is good, putting the 80 lower on the existing 90 would mean you need to move up a couple inches of pitch or vice versa if you went the other way...."
 
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